Affordable Access

Cyclic AMP as a modulator of polarity in polycistronic transcriptional units.

Authors
Publication Date
Source
PMC
Keywords
  • Research Article
Disciplines
  • Biology

Abstract

The degree of natural polarity in the lactose and galactose operons of Escherichia coli is affected by adenosine 3',5'-cyclic monophosphate (cAMP). This effect, mediated by the cAMP receptor protein, is exerted at sites distinct from the promoter. Experiments performed with a mutant bearing a thermosensitive rho factor activity indicate that cAMP relieves polarity by interfering with transcription termination. Conflicting results in the literature concerning the role of cAMP receptor protein and cAMP in galactose operon expression can be reconciled by the findings that cAMP stimulates the expression of operator distal genes without significantly affecting the proximal genes. Therefore, it appears necessary to reevaluate the classification of the galactose operon as exhibiting cAMP-mediated catabolite repression at the level of transcription initiation.

There are no comments yet on this publication. Be the first to share your thoughts.